Networking - Get computers talking

When it comes to networking, there's a lot to know. I'll try to cover the basics, but keep in mind, there are 2 inch thick books written on the subject.

Hardware:

Hub - A dumb device that does nothing other than provide additional ethernet ports. Caution should be taken with the use of hubs as there's nothing to prevent data packets from bumping into each other. Too many computers connected by a large hub can cause packet loss due to packet collisions.

Switch - Similar to a hub with one major difference. Switches have little traffic cops directing the flow of traffic, preventing packet collisions. On a wired network in an office building, switches will often be used to connect multiple floors together on the same network.

Router - A router works totally different than a switch or a hub. It uses NAT (Network Address Translation - converts external public IP addresses to internal private IP addresses) and a DHCP server (a small server that distributes internal IP addresses to each connected computer). A wired network would require at least one router to take your internet provider's single IP address and convert it into multiple internal private IP addresses. The only way to get around using a router would be a dedicated server running DHCP, but that's rarely seen.

Wireless Router - Takes the technology of a router and adds wireless capability to it. There are different types of wireless protocols and currently the most common ones are wireless G, N, and AC. I'll have more on that later.

There are three sections of IP addresses designated as internal private IP addresses. These are:

10.0.0.0 – 10.255.255.255 (Large networks with the highest number of possible IP addresses)
172.16.0.0 – 172.31.255.255 (Mid-range networks used in a small office building with 2-3 floors)
192.168.0.0 – 192.168.255.255 (Small networks usually used for home use)

So, your internet provider gives you one external IP address using a DSL or cable modem with no router. That address is assigned to only one computer and that is the only one that can get online. Each computer has to have it's own IP address. There are two solutions. Get more IP addresses from your provider (good luck with that), or use a router to take that single IP address and, using NAT and a DHCP server, distribute multiple internal private IP addresses to all the connected computers.

Scenerio: Your Internet provider assigns 214.232.154.167 to your home and they give you a DSL or cable modem (not a wireless router). You would connect a router to your modem and the router gets assigned 214.232.154.167 on the internet side. On the LAN side, the router uses NAT to convert that address to 192.168.0.1 - an internal private ip address. This IP address becomes known as the gateway as it is the router itself. Now DHCP kicks in and distributes IP addresses starting at 192.168.0.2 and increases 1 number for each computer the router sees. Problem: Your wired router only has 4 ethernet ports and you have 8 computers. Here you would connect a switch to one of the LAN ports on the router and then connect ethernet cables to the switch. A lot of this has been simplified by using wireless networking.

Wireless networking: Instead of relying on ethernet cables, the DHCP server broadcasts a name (SSID) for the router and a password. If your computer passes authentication, it is given an IP address and you connect to the internet. There are two bands currently being used for wireless networking: 2.4 GHz and 5.0 GHz. The most commonly used band is 2.4 GHz as it penetrates walls better and has further range. The 5.0 GHz band is mainly used for streaming movies to a blu-ray player or other media devices. It's advantages are less interference, but shorter range. On the 2.4 GHz band there are 2 protocols: Wireless G, and Wireless N. Wireless N can transfer data at speeds up 450 Mbps. Wireless G is limited to 54 Mbps. Now If you're still with me there is one more variable: bandwidth. Wireless N routers can use 20 or 40 MHz bandwidth. Think of bandwidth as lanes on a highway. 20 MHz is comparable to 4 lanes, 40 MHz is comparable to 8 lanes. If you have an AC router it can use 80 MHz or 16 lanes of traffic, But only on the 5.0 GHz band. The more lanes, the more traffic can flow at any given time means faster speeds.

Security: Obviously with all this data being transferred over the air, you don't want strangers gaining access to it. There are three types of security or encryption available: WEP, WPA, and WPA2 Personal. I won't cover WPA2 Enterprise as it's outside the scope of the average user. The best encryption is WPA2 Personal and that's what I recommend.

Routers are used for more than giving out IP addresses. If you have an office building sharing a T1 line (very fast connection), and the main floor is a lawyers office and the 2nd floor is a medical clinic. A router can be used to give the main floor 192.168.x.x addresses, and the 2nd floor can be assigned 10.x.x.x addresses. This gives both floors an internet connection, but they cannot see each other on the network keeping your health records secure from the lawyers.

Obviously this was a very complex article and I've only touched the basics. As I've stated entire books are available on networking. At least you should now have a better understanding of networking and how it works.